One of the major challenges of installing and operating optical data communications systems, such as those often used to communicate data within cellular networks, is maintaining optical power levels within the power windows required for optical receivers to correctly function. One way the communications industry has handled this requirement is by installing fixed inline optical power attenuators in the physical layer of an optical communications system. However, problems arise in this solution because every network facility is different in terms of optical power loss due to equipment and varying fiber optic cable lengths. To implement the fixed optical power attenuator solution, network operators must deploy technicians to manually take optical power measurements at one location while calibrating attenuators at other locations. Besides the high implementation and operational expenses associated with fixed inline attenuators, their presence in the physical layer of a communications network creates additional points for introducing contamination and network failures.
Feedback control variable optical power attenuators have been proposed as one solution for managing optical power. One problem experienced when using feedback controlled variable optical power attenuators is a phenomenon known as “sticking.” When sticking occurs, the affected optical power attenuator no longer responds to feedback signals but instead “sticks” at some constant attenuation. When sticking occurs, automated control of optical power is no longer possible as the variable optical power attenuators essentially becomes a fixed inline attenuator. The resulting attenuation may produce optical power levels that are too low to support digital communication. The exact point where sticking occurs varies from one optical power attenuator to another, and drifts for any one optical power attenuator over time or as a function of environmental factors such as temperature.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for improved methods and systems for variable optical power attenuator control.